1. Field of the Invention
The present invention relates to a bicycle wheel rim adapted for mounting a bicycle tire without an inner tire body, more particularly to a bicycle wheel rim which can facilitate inflation of the bicycle tire.
2. Description of the Related Art
FIG. 1 illustrates a conventional bicycle wheel rim 1 for mounting a bicycle tire 2 that does not require an inner tire body. The bicycle tire 2 has left and right abutment edges 21. The wheel rim 1 has left and right annular tire retaining walls 11, and an annular connecting wall 12. The connecting wall 12 has left and right wall parts 123, and an indented intermediate wall part 122 that defines an annular receiving groove 126. The intermediate wall part 122 has a pair of curved wall portions 125a connected respectively to the left and right wall parts 121. Each of the curved wall portions 125a has a convex surface 125 connected to the intermediate wall part 122, and an inclined surface 124 connected to the respective one of the left and right wall parts 123.
During installation, the bicycle tire 2 is first sleeved on the wheel rim 1 such that the abutment edges 21 are initially received in the receiving groove 126 to permit subsequent inflation of the bicycle tire 2 via a valve unit (not shown) mounted on the wheel rim 1. Before inflation, the bicycle tire 2 is in a state indicated by the phantom lines in FIG. 1. During inflation with the use of a high pressure air compressor, the abutment edges 21 slide respectively along the convex surfaces 125, and move past the convex surfaces 125 to reach the left and right wall parts 121 almost simultaneously. However, when the bicycle tire 2 is inflated using a manually operable or low pressure air compressor, points on the abutment edges 21 along the length thereof normally do not move at the same time on the convex surfaces 125. As a result, the bicycle tire 2 may be twisted during inflation, and air leakage may occur.
Moreover, due to the inclined surfaces 124 that are connected to the left and right wall parts 123, it is possible that one of the abutment edges 21, or a part of any of the abutment edges 21, will move past the adjacent inclined surface 124 and toward the receiving groove 126 when the bicycle tire 2 runs into an obstacle. Secure retention of the bicycle tire 2 on the conventional bicycle wheel rim 1 cannot be ensured.
Therefore, the main object of the present invention is to provide a bicycle wheel rim which can facilitate inflation of a bicycle tire even when a low pressure or manually operable air compressor is in use.
Accordingly, the bicycle wheel rim of the present invention is adapted for mounting an inflatable bicycle tire with left and right abutment edges, and includes an annular rim body with a central axis. The rim body includes spaced-apart annular left and right tire retaining walls, and an annular connecting wall extending between and interconnecting the left and right tire retaining walls. Each of the left and right tire retaining walls has a radial outer end distal from the central axis and adapted to engage a respective one of the left and right abutment edges of the bicycle tire. The connecting wall cooperates with the left and right tire retaining walls to confine a tire retaining space adapted for retaining the bicycle tire. The connecting wall has left and right wall parts, each having an outer terminating edge adjacent to a respective one of the left and right tire retaining walls, and an inner terminating edge opposite to the outer terminating edge. The connecting wall further has an intermediate wall part extending between and interconnecting the inner terminating edges of the left and right wall parts. The intermediate wall part is indented radially and inwardly relative to the left and right wall parts so as to define an annular receiving groove that opens radially and outwardly and that is communicated with the tire retaining space. The receiving groove is adapted to receive the abutment edges of the bicycle tire upon installation of the bicycle tire on the rim body. Each of the left and right wall parts has a radial outer surface which faces radially and outwardly and which is formed with an annular rib that extends longitudinally along the respective one of the left and right wall parts such that the radial outer surface is defined with an outer section extending between the rib and the outer terminating edge, and a flat inner section extending between the rib and the inner terminating edge. The rib projects radially and outwardly relative to the inner and outer sections of the radial outer surface, and has a first stop surface connected to the inner section and a second stop surface connected to the outer section.